The invention relates to a colour display tube comprising an envelope including a display window, a colour selection electrode, and suspension means for suspending the colour selection electrode from the display window, which suspension means each comprise a first element which is secured to the colour selection electrode and a second element which is secured to the display window, the first element having an aperture and the second element having a portion which engages the said aperture.
A colour display tube of the type described in the opening paragraph, having suspension means in the vicinity of the four corners of a substantially rectangular display window is known from U.S. Pat. No. 4,644,222.
In the colour display tube described therein, the first element of each suspension means is a flat resilient element which is oriented substantially perpendicular to the path of electron beams to be deflected to the relevant corner, and the second element is a metal pin which is secured at one end to the corner of an upright edge of the display window and at the other (free) end has a convex portion. This pin is made in one piece of tinplate or moulded or turned from a rod-like metal body.
An important aspect of the suspension of the colour selection electrode is the dimensional accuracy with which the said (convex) portion of the second element of each suspension means engages the aperture of the first element. The color selection electrode is used in the photographic process of providing a display screen on the display window, repeated mounting and demounting of the colour selection electrode is necessary. In this process the insertion reproducibility, i.e. the degree of reproducibility of the location of the colour selection electrode is very important. This insertion reproducibility is influenced by the accuracy with which the (convex) portion and the of this portion of the second element of each suspension means is made.